The division of legislative powers in the Constitution Act, 1867 is the most important textual expression of the federal principle that is at the heart of the Canadian constitutional order. The judiciary has the responsibility of interpreting these provisions and thus of determining the boundaries of the law-making powers of Canadian legislative bodies. In performing this high-stakes task, the courts have developed a rich jurisprudence that draws on text, history, structure, and principle. In recent decades, the Supreme Court has articulated a “modern” or “co-operative” approach that interprets both federal and provincial legislative powers generously, and tolerates a high degree of overlap and interplay between them. Despite this commitment to maximizing the democratic space available to all Canadian legislatures within their respective areas of jurisdiction, some doctrines developed by the courts have had asymmetric effects that favour the federal Parliament.